In July 1967, Jocelyn Bell Burnell noticed a “bit of scruff” in the radio data she was receiving at the Mullard Radio Astronomy Observatory. Together with her Ph.D. advisor Antony Hewish, she zeroed in and followed up on the strange signal. On Feb. 24, 1968, the pair (together with three additional co-authors) published in the journal Nature the first paper on the sources that would come to be known as pulsars.
That first paper proposed “a tentative explanation of these unusual sources in terms of the stable oscillations of white dwarf or neutron stars;” we now know that pulsars (a term coined separately in 1968) are indeed rotating neutron stars beaming radiation from their poles. Neutron stars, the remnants of supernovae, are randomly oriented in space — but sometimes, they’re oriented just right, and their beams sweep over Earth, much like the light from a lighthouse. Pulsars offer a way to test ideas about stellar evolution and theories like General Relativity; they are also ideal beacons for deep-space navigation, and have even been used to potentially point alien civilizations back to Earth (via the Pioneer 10 plaque).
